RESUMEN
In this report, we describe a national-scale monitoring of the SARS-COV-2 (SC-2) variant dynamics in Israel, using multiple-time sampling of twelve wastewater treatment plants. We used a combination of inclusive and selective quantitative PCR assays that specifically identify variants A19 or B.1.1.7 and tested each sample for the presence and relative viral RNA load of each variant. We show that between December-2020 and March-2021, a complete shift in the SC-2 variant circulation was observed, where the B.1.1.7 replaced the A19 in all examined test points. We further show that the normalized viral load (NVL) values and the average new cases per week reached a peak in January 2021, and then decreased gradually in almost all test points, in parallel with the progression of the national vaccination campaign, during February-March 2021. This study demonstrates the importance of monitoring SC-2 variant dynamics on a national scale through wastewater sampling. It also provides a proof-of-concept methodology for continuous surveillance by using a combination of inclusive and selective PCR tests, which is far more amendable for high throughput monitoring compared with sequencing. This approach may be useful for real-time dynamics surveillance of current and future variants, such as the Omicron (BA.1) variant. SynopsisThis study describes the continuous monitoring of the SARS CoV-2 variant B.1.1.7 circulation in wastewater in Israel using a positive/negative quantitative PCR assay.
RESUMEN
The COVID-19 pandemic created a global crisis impacting not only healthcare systems, but also world economies and society. Recent data have indicated that fecal shedding of SARS-CoV-2 is common, and that viral RNA can be detected in wastewater. This suggests that wastewater monitoring is a potentially efficient tool for both epidemiological surveillance, and early warning for SARS-CoV-2 circulation at the population level. In this study we sampled an urban wastewater infrastructure in the city of Ashkelon, Israel, during the end of the first COVID-19 wave in May 2020 when the number of infections seemed to be waning. We were able to show varying presence of SARS-CoV-2 RNA in wastewater from several locations in the city during two sampling periods. This was expressed as a new index, Normalized Viral Load (NVL), which can be used in different area scales to define levels of virus activity such as red (high) or green (no), and to follow morbidity in the population at tested area. Our index showed the rise in viral load between the two sampling periods (one week apart) and indicated an increase in morbidity that was evident a month later in the population. Thus, this methodology may provide an early indication for SARS-CoV-2 infection outbreak in a population before an outbreak is clinically apparent. HIGHLIGHTSO_LIDetecting the presence of SARS-CoV-2 virus RNA in urban wastewater C_LIO_LIThe city sewer system may provide an early indication for SARS-CoV-2 infection and may be used as early warning for SARS-CoV-2 outbreaks C_LIO_LINVL index defines various infected urban zones from red (high) to green (low) C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/20215244v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@360a84org.highwire.dtl.DTLVardef@1ec8004org.highwire.dtl.DTLVardef@1c8ae93org.highwire.dtl.DTLVardef@3d670c_HPS_FORMAT_FIGEXP M_FIG C_FIG